This invention relates to electronic test sockets, and more particularly to sockets for testing memory modules.
Some of the most widely used electronic components are small printed-circuit board (PCB) daughter cards known as memory modules. Personal computers (PC""s) and other electronic systems use memory modules. Memory modules are plugged into sockets on a motherboard, reducing a need to directly mount individual memory chips on the motherboard. The memory modules are built to meet specifications set by industry standards, thus ensuring a wide potential market and low cost. Single-inline-memory modules (SIMM) and dual-inline-memory modules (DIMM) are two types of memory modules.
Memory modules can be tested using general-purpose electronic-component testers, but these testers tend to be quite expensive. Memory modules can also be tested in PC-based testers. Since PC""s are very inexpensive, test costs can be significantly reduced. The memory modules being tested can be inserted into memory module sockets on a PC motherboard, which executes a memory test program to test the memory modules. See as examples U.S. Pat. Nos. 6,178,526, 6,415,397, 6357023, and 6,351,827.
A drawback to using a PC motherboard for testing memory modules is that the memory module sockets can become worn with use, since thousands of different memory modules may be inserted and removed for testing. The standard memory module sockets on a PC motherboard are not designed for such frequent replacement of the memory modules. Specialized test sockets such as Yamaichi and zero-insertion-force (ZIF) sockets may replace the standard memory module sockets on PC motherboards used as testers.
A variety of ZIF sockets are known. Some ZIF sockets have a fixed housing that surrounds a membrane that has metal contact pads printed on it. The membrane is flexible, allowing it to move slightly as the memory module is inserted into the test socket. The flexible nature of the membrane reduces the force needed to insert the memory module into the test socket, compared with the force needed to insert the memory module into a rigid test socket that has metal contacts attached directly to the rigid housing. An elastic material known as an elastomer may be placed between the membrane and the housing to accommodate differences in module thickness.
While such test sockets are useful, an improved ZIF test socket is desired. Some pressure from the membrane is needed to make good electrical contact once the memory module is inserted into the test socket. The membrane may still exert some force on the memory module during insertion and removal, which may cause damage such as scratching the contact pads of the memory module as the module""s contacts slide along the membrane.
The test socket itself may also become damaged during insertion of the memory module. The sharp edges of the module""s PCB may scratch the membrane or the metal contacts on the membrane as the memory module is slid into the test socket.
Accurate placement or alignment of the memory module into the test socket may be needed. A test socket with an alignment guide is desired to ease alignment requirements and facilitate testing. A test socket with reduced insertion force is desirable.